Strategies for Using Automotive Textiles-Manufacturing Techniques and Applications

Journal of Safety Engineering 2012, 1(1): 7-16 DOI: 10.5923/j.safety.20120101.02

Strategies for in Automobile: Strategies for Using Automotive Textiles-Manufacturing Techniques and Applications

Kunal Singha

Department of Textile Technology, Panipat Institute of Engineering & Technology, Harayana, India

Abstract The safety in automobile is become importance in the modern scenario. The textile product can be use in this purpose in the form of various safety devices like air bag, seat belt, car interior, Power steering filters, Abs brake filter, tire cord production, lining, covering, cushion components, design interior etc. The different grade textile fibers as polyester, nylon, PVC, acrylic, viscose/cotton etc can be the potential option for the new emerging field name called automotive textile. Keywords Air Bag, Seat Belt, Car Interior, Tire Cord Production, Lining, Covering, Cushion Component, Design Inte- rior, Polyester, Nylon, PVC, Automotive Textile

which is triggered primarily by the factors like increase in 1. Introduction income and standard of living of the middle class Indian families and Indian government liberalization measures. Textiles are no more limited for use as apparels clothing is Further, as travel has become the integral part of everyone’s just are but not the only purpose of textiles with the rapid life, issues such as comfort and safety have taken on a right changes in the social economic structure of our society. priority. All these factors clearly indicate brilliant prospect Many efforts are made to some and protect human life. for automotive textile industry which lead to increased de- Automotive textiles happens to be the rewarding sector mand of the technical textiles components used in automo- finding extensive use of technical textiles in the product biles[3, 4]. It is expected that India will be the leading car categories viz. interior trims, safety devices like seat belts producer (15%) by 2015. Another reason for large growth in and airbags, carpets, filters, battery separators, hood liners, the automotive textiles is that India is a low cost manufac- hoses & belt reinforcement. Textiles, which constitute ap- turing base. proximately 20-25 Kgs in a car, are not only used for en- hanced aesthetic of automotives but also for sensual comfort Table 1. Textiles in automotives[1] & safety. Additionally, few textile products found their ap- Breakup of automotive Textiles Share % plications as design solutions to engineering problems in the Sl.No form of composites, tyre reinforcement, sound insulation & 1 Carpets (Including Car Mats) 33.3 vibration control. Apart from woven & knitted constructions, Nonwovens also find applications in transport textiles due to 2 Upholstery (Seating Fabric) 18 certain advantages served by them. The use of textiles (Table 3 Pre-assembled interior components 14 1) in automotive applications includes floor coverings; up- 4 Tyres 12.8 holstery; belts, tubes and tapes; tyre cord; safety belts; air- 5 Safety Belts 8.8 bags; components; and filters[1,2] 6 Air bags 3.7 1.1. Market for Automotives 7 Others 9.4 Total 100 THE Indian automotive industry has experienced an un- precedented boom in the recent years. From 2007-2015 India will contribute 16% to the global automotive textiles. This is due to the sudden increase in the demand of automotives 2. Seat Belt: Engineering Principle The seat belt is an energy-absorbing device that is de- * Corresponding author: [email protected] (Kunal Singha) signed to keep the load imposed on a victim's body during a Published online at http://journal.sapub.org/safety crash down to survivable limits. Fundamentally, it is de- Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved signed to deliver non-recoverable extension to reduce the

8 Kunal Singha: Strategies for in Automobile: Strategies for Using Automotive Textiles-Manufacturing Techniques and Applications deceleration forces, which the body encounters in a crash. same direction unless acted upon by an unbalanced force. Basically, it is designed to offer non recoverable extension to Thus, driver continues in motion, sliding forward along the decrease the deceleration forces that the body comes across seat. A driver in motion tends to stay in motion with the same in a crash. Non recoverable extension is significant to pre- speed and in the same direction, unless acted upon by the vent the occupants from being restrained into their seats and unbalanced force of a seat belt. Seat belts are used to provide sustaining whiplash injuries right away after a collision. An safety for passengers whose motion is governed by Newton's efficient seat belt will only permit its wearer to move forward laws (Figure 1). The seat belt provides the unbalanced force, a maximum of about 30 cm to avoid contact with any fixed which brings driver from a state of motion to a state of rest[1, parts of the car. Seat belt was invented concurrently in 9]. United States and Sweden. Earlier seat belts were fixed and Assume, car speed is 13.41 m/s, driver’s weight is 50 kg, adjusted manually by the wearer. With the introduction of then what will be the impact force acting on the car driver? automatic belts today wearer has more freedom to move[6]. If driver is wearing a non-stretchable seat belt, stopping distance is 0.304 mt. 2.1. Need for Seat Belt Impact force on driver =[0.5x 50x(13.41)2] / 0.304 = In an auto smash, seat belts prevent ejection from a mov- 14788.5 N = 1.5 tons 2 ing car and stop people going through the windshield as the Deceleration of driver = 14788.5/50 = 295.77 m/s vehicle comes to a sudden stop. Seat belts also minimize If driver is without seat belt, suppose stopping distance is injuries due to impact with the vehicle's hard interior; they 0.0608 mt. 2 ensure better control of the car. Seat belts also hold people in Impact force on driver =[0.5x 50x(13.41) ] / 0.0608 = position for the protective cushioning, if there's an air bag. At 73942.5 N = 7.5 tons 2 speeds under 25 mph, seat belts give adequate protection, but Deceleration of driver = 73942.5/50 =1478.8 m/s ; now if at higher speeds, air bags help to prevent the violent forces driver is wearing stretchable seat belt, stopping distance is exerted on the neck and head in frontal crashes[5, 7]. 0.456 mt (Figure 2)

Figure 1. Forces in Car Crashes

2.2. Scientific Approaches towards Seat Belt Figure 2. Safety and signifiance of the seatbelt It’s a simple Newton’s first law of motion and law of en- Force on driver =[0.5x 50x(13.41)2] /0.456 = 9467.65 N = ergy conservation. According to Newton’s first law of mo- 0.96 ton and deceleration of driver = 9467.65/50 = 189.353 tion an object at rest tends to stay at rest and an object in m/s2 motion tends to stay in motion with the same speed and in the A moderate amount of stretch in a seatbelt harness can

Journal of Safety Engineering 2012, 1(1): 7-16 9

extend the stopping distance and reduce the average impact body of the webbing. Low longitudinal stiffness and thinner force on the driver compared to a non-stretching harness. If web gives good winding performance with use of smooth the belt stretched 0.125 mt. it would reduce the deceleration monofilament weft yarns[11]. to 189.353 m/s2 and the average impact force to 0.96 ton compared to 295.77 m/s2 and 1.5 tons for a non-stretching 2.5. Major Machineries Required for the Manufacture of seat belt. Either a stretching or non-stretching seat belt re- Seat Belt Webbings are duces the impact force compared to no seat belt[8]. High speed automatic needle looms, Warp yarn tension 2.3. Raw Material and Manufacturing Method: control device, Tape collection machine Cone Creel of 600 Constructional Details ends, Continuous Dying machine Steam Boiler, Compres- sor[12]. Raw material used for seat belt webbings are Nylon, PET and its derivatives like HTPY. Nylon was utilized in some 2.6. Major Global Manufacturers of Seat Belts and early seat belts, but due to of its higher UV degradation Webbing resistance; polyester is now widely used worldwide and also polyester scores over nylon because of lower extensibility Autoliv, Sweden, Key Safety Systems, USA, TRW, and higher stiffness. Seat belt structures can be single layer Germany, Delphi Corporation, USA, Ribbons Limited, or double layer and manufactured on needle looms with plain UK[10,13]. weave, twill weave, satin weave. Normally 2/2-twill structure is used (Table 2). The needle loom used presently is 2.7. Seat Belt Quality Details: Requirements shuttleless and capable of delivering over 1000 picks per The seat belt is required to have the properties: Static load minute[10]. bearing capacity upto 1500 kg and extensibility upto 25-30%, A typical seat belt is made of 320 ends of 1,100 dtex Abrasion resistance, Heat and light resistance, Light weight, polyester each. Most weft yarns made from polyester are Flexibility for use[13, 14]. 550dtex. Commonly used seat belt webbing is a narrow fabric measuring 46mm wide. Commercial needle looms can 2.8. Performance Tests and Standard for Seat Belt accommodate six weaving stations simultaneously side by side. In case of nylon seat belts, the warp yarns are 180 dtex Tests are carried out for ascertaining the mechanical per- and the weft is either 470 or 940 dtex. Normally, 1000-1500 formance of the webbing as per BSI and the SAE on the denier used for main warp yarns, 250-500 denier used for some aspects like; width, thickness , breaking strength and selvedge yarns and same denier or slightly higher denier as elongation for dry and wet webbing, abrasion resistance at selvedge yarns used for weft. Typically, 320 ends of 1100 various environmental conditions and in contact with buck- dtex or 260 ends of 1670 dtex yarn. This structure permit les and fittings, influence of extreme environmental condi- highest yarn packing within a given area for highest strength tions and temperatures, rubbing fastness, microbial resis- and sometimes-coarser yarns are used for good abrasion tance[11]. resistance[13]. 2.9. Recent Developments in Seat Belt: Smart Belt 2.4. Manufacturing Method of Seat Belts Used in Autoliv's Smart Belt System uses a switch mechanism to Automobile Car adapt its restraining force – and hence the load on the oc- In the needle loom, the weft is inserted from one side of cupant – to the severity of the crash. In a crash, the Smart the warp sheet and here a selvedge is formed. The other side Belt System starts – as in most modern seatbelt systems – by of webbing is held by an auxiliary needle, which manipulates tightening the belt, using a pyrotechnic pretensioner. This a binder and a lock thread. Once these are combined with the eliminates slack and makes it possible to release some web- weft yarn, a run-proof selvedge is created. Special care is bing at a later stage, if the load on the occupant becomes too taken when constructing the selvedge to ensure it is abrasion high. On the Smart Belt System, the Smart Belt can adapt its resistant. It is equally important to ensure that the selvedge is restraining force – and hence the load on the occupant – to soft and comfortable to wear. In a loom, needle used to move the crash severity. If the vehicle is equipped with an occu- monofilament and multifilament weft yarn across width of pant weight sensing systems, it is also possible to adjust the the web in single shed. A high tension applied to mono- seatbelt load individually to each occupant. This is an im- filament compared to multifilament yarn so that it doesn’t portant advantage since smaller, lighter weight occupants, protrude beyond selvedge. For selvedge single ply warp yarn such as many women, are more susceptible to high belt loads is used with reverse twill weave that gives close packing and than the average person, and these individuals do not need soft, round edge selvedge. Monofilament weft yarns are rigid the same restraining force as a larger occupant[15]. yarn that provides good stiffness across web and high resil- • Trunk Belt: Safety belts which protect fragile goods iency. Monofilament weft yarns are under high tension and prevent luggage from penetrating into the passenger which controls webbing softness and round shape together compartment in, for instance, cars with folding rear with catch cord yarns and finer warp yarns in selvedge than seats[16].

10 Kunal Singha: Strategies for in Automobile: Strategies for Using Automotive Textiles-Manufacturing Techniques and Applications

Table 2. Materials used in seat belt manufacturing

Material Body warp yarn Selvedge warp yarn Weft yarn Binder thread Locking thread

PA/PET 1260 D/108(fil.) 250 D/24(fil.) 500D/48(fil.) 100 D/18(fil.) 250 D/24(fil.)

PA/PET 846/2 D 846 D (mono) 423 D (multi) 220 D 150 D

• Inflatable belts: The inflatable seat belt is an amalga- strained, they will continue moving at whatever speed the car mation of the air bag and the seat belt. This belt is held by is traveling at, even if the car is stopped by a collision. weak stitches that burst open when the belt is inflated. Under impact the belt gives 450% more surface area than the nor- mal flat belt. These belts could be fitted in the rear seats of the automobile to replace use of air bags in that compartment. A folded envelop of 3” is covered by 2” face fabric, which is stitched. A folded envelop is rubber coated. Today’s enve- lopes are made from urethane or silicon to make thin, gas leakage proof, high strength, heat resistance and when crash Figure 3. Force distribution on body during collision[3] occurs a gas fills and inflates the envelope. The face fabric (web) is made of a resin such as PET. Today’s cover fabric Stopping an object's momentum requires force acting uses warp knitted structure. As warp knitted fabric has good over a period of time. When a car crashes, the force strength, good stretching characteristics, comfortable. Warp required to stop an object is very great because the car's knit uses yarn of 3000 denier or below. By using such belts momentum has changed instantly while the passengers' has kinetic energy of passenger is distributed over a larger area, not there is not much time to work with. The goal of any therefore load experienced by a passenger is small and pas- supplemental restraint system is to help stop the passenger senger protected very effectively[17]. while doing as little damage to him or her as possible. What an airbag wants to do is to slow the passenger's speed to zero with little or no damage. The constraints that it has to work 3. Air Bags within are huge. The airbag has the space between the passenger and the steering wheel or dashboard and a fraction of Airbags inflate, or deploy, quickly -- faster than the blink a second to work with. Even that tiny amount of space and of an eye. Imagine taking one second and splitting it into one time is valuable, however, if the system can slow the pas- thousand parts. In the first 15 to 20 milliseconds, airbag senger evenly rather than forcing an abrupt halt to his or her sensors detect the crash and then send an electrical signal to motion[3]. fire the airbags. Typically a squib, which is a small explosive device, ignites a propellant, usually sodium azide. The azide burns with tremendous speed, generating nitrogen, which inflates the airbags. Within 45 to 55 milliseconds the airbag is supposed to be fully inflated. Within 75 to 80 milliseconds, the airbag is deflated and the event is over. When airbags work properly, they dramatically reduce the chance of death or serious injury. However, the speed with which airbags inflate generates tremendous forces. Passengers in the way of an improperly designed airbag can be killed or significantly injured. Unnecessary injuries also occur when airbags Figure 4. The airbag and inflation system stored in the steering wheel[19] inflate in relatively minor crashes when they're not 3.2. Airbag Inflation needed[16]. The goal of an airbag is to slow the passenger's forward motion as evenly as possible in a fraction of a second. There 3.1. Engineering Principle: Law of Motion behind Air are three parts to an airbag that help to accomplish this feat: Bags · The bag itself is made of a thin, nylon fabric, which is The moving objects have momentum (the product of the folded into the steering wheel or dashboard or, more recently, mass and the velocity of an object). Unless an outside force the seat or door. acts on an object, the object will continue to move at its · The sensor is the device that tells the bag to inflate. present speed and direction. Cars consist of several objects, Inflation happens when there is a collision force equal to including the vehicle itself, loose objects in the car and, of running into a brick wall at 10 to 15 miles per hour (16 to 24 course, passengers (Figure 3). If these objects are not re- km per hour). A mechanical switch is flipped when there is a

Journal of Safety Engineering 2012, 1(1): 7-16 11

mass shift that closes an electrical contact, telling the sensors coated nylon. Two types of commonly used coatings are that a crash has occurred (Figure 4). The sensors receive Silicone and Neoprene (Table 3). In general, coated materi- information from an accelerometer built into a micro- als are used for driver's side airbags and side impact bags, chip[19]. while passenger side airbags are made from uncoated nylon

The airbag's inflation system reacts Sodium azide (NaN3) materials[8]. with potassium nitrate (KNO3) to produce nitrogen gas. Hot blasts of the nitrogen inflate the airbag.[3] Table 3. Comparision of fibre properties[8] Early efforts to adapt the airbag for use in cars bumped up Properties Nylon6,6 Polyester 3 against prohibitive prices and technical hurdles involving the Density(kg/m ) 1140 1390 Specific Heat Capacity (kJ/kg/k) 1.67 1.3 storage and release of compressed gas. Researchers won- Melting Point ( ) 260 258 dered: Softening Point ( ) 220 220 · If there was enough room in a car for a gas canister Energy to melt (kJ/Kg)℃ 589 427 · Whether the gas would remain contained at high ℃ pressure for the life of the car 3.4. Manufacturing Techniques of Airbag Fabrics · How the bag could be made to expand quickly and re- An airbag for deployment outside of a vehicle is made liably at a variety of operating temperatures and without from a fabric that is coated on at least one of the surfaces of emitting an ear-splitting bang the fabric. The airbag fabric may be coated to increase the They needed a way to set off a chemical reaction that strength of the fabric so that the fabric is reinforced. By would produce the nitrogen that would inflate the bag. Small increasing the strength of the fabric, breakage of the airbag solid-propellant inflators came to the rescue in the 1970s. can be minimized. By employing an airbag that is made from a fabric that is coated on at least one of the surfaces of the fabric, the airbag is less likely to decrease in strength when the airbag comes into contact with a foreign object that presses or scratches against the airbag. The vehicle may be a motorcycle, automobile, train, or other vehicle[9]. • Coated Base Fabric for Air Bags: A coated airbag base fabric made of a textile fabric that has an excellent air barrier property, high heat resistance, improved mountability, and compactness and excellent adhesion to a resin film is characterized in that at least one side of the textile fabric is

Figure 5. The inflation system uses a solid propellant and an igniter[18] coated with resin, at least part of the single yarns of the fabric are surrounded by the resin, and at least part of the single The airbag system ignites a solid propellant, which burns yarns of the fabric are not surrounded by the resin. An airbag extremely rapidly to create a large volume of gas to inflate is characterized by using such a coated airbag base fabric. A the bag. The bag then literally bursts from its storage site at method for manufacturing the coated airbag base fabric is up to 200 mph (322 kph) faster than the blink of an eye. A characterized by applying a resin solution having a viscosity second later, the gas quickly dissipates through tiny holes in of 5–20 Pas (5000– 20,000 cP) to the textile fabric using a the bag, thus deflating the bag so you can move. Even though knife coater with a sharp-edged coating knife at the contact the whole process happens in only one-twenty-fifth of a pressure between the coating knife and the fabric of 1–15 second, the additional time is enough to help prevent serious N/cm[9, 10]. injury (Figure 5). The powdery substance released from the • Laminated Material for Airbag: Disclosed is a airbag, by the way, is regular cornstarch or talcum powder, polymer film, preferably a polyamide polymer film, which which is used by the airbag manufacturers to keep the bags comprises at least one first layer and a second layer and is pliable and lubricated while they're in storage[3]. laminated onto a fabric. The material of the first layer has a glass transition temperature of less than 10oC while the ma- 3.3. Manufacturing Process: Raw Materials (Fibers) for terial of the second layer has a glass transition temperature of Air Bags less than 20oC. Preferably, the polymeric materials contain Air bag fabrics are made of Nylon 6,6 multifilament portions of polyamide blocks[12]. yarns with counts from 235 to 940 tex. Air bag fabrics are generally dense which a challenging task to weave is. Ten- 3.5. Method of Manufacturing an Airbag sile strength, elongation, tear proportion resistance and • Positioning a first air bag part having at least two con- weight requirement of air bag fabric are critical. Air per- nection sections in an opposing relationship to a second air meability of air bag fabric should be uniform across the bag part having at least two attachment sections, the at- whole width of the fabric[13, 17]. There are currently two tachment and connection sections also opposing each other principle material types which are used in the manufacture • Coating at least one opposing surface of the first and of airbags. They are uncoated nylon (polyamide 66) and second air bag parts with polyurethane, wherein the connec-

12 Kunal Singha: Strategies for in Automobile: Strategies for Using Automotive Textiles-Manufacturing Techniques and Applications tion or attachment sections located on the at least one op- better protection in some side collisions. Another option for posing surface are coated as well. head protection in side impacts is the curtain airbag[8,10,17]. • Contacting the opposing connection and attachment sections with each other; and • Heating the first and second air bag parts to thereby 4. Automotive Filters weld the first and second airbag parts together at the attachment and connection sections to form an inflatable re- Performance of any automotive engine mainly depends on gion between the first and second air bag parts and a first engine technology and filter system used. Automotive filter non-inflatable region located within the inflatable re- business is however mainly concerned with air filters, oil gion[17]. filters, fuel filters and cabin filters. The performance of an automobile is bolstered significantly by the presence of high 3.6. Types of Airbags performance filter media in the engine compartment and in various other locations. The purpose of filter is to control • Air bags For Frontal Injury , Side Air bags for cars , contamination through achieving a balance between the Airbags for Motorcycle , Pedestrian Protective Air Bags[8] sources of contamination and the ability of a system to tol- 3.7. The Future of Airbags erate contamination. The ultimate goal is to balance filtration performance with the desired cleanliness level. In the mod- Until recently, most of the strides made in auto safety were ern car machines a varieties of textile fibers are used for auto in front and rear impacts, even though 40 percent of all se- filter preparations as per as the suitable requirements and end rious injuries from accidents are the result of side impacts, uses (Table 4). and 30 percent of all accidents are side-impact collisions. • Automotive Oil Filter: Oil Filter Media, Particle size Many carmakers have responded to these statistics (and the retention (filtration efficiency), Dirt-holding capacity Re- resulting new standards) by beefing up doors, door frames sistance to oil flow and floor and roof sections. But cars that currently offer side • Automotive Fuel Filter: Diesel Fuel Filters, Air Filter, air bags represent the new wave of occupant protection. Automatic Transmission Filter, Coolant Filter[7, 12] Engineers say that designing effective side airbags is much more difficult than designing front airbags. This is because much of the energy from a front-impact collision is absorbed 5. Automotive in Car Interior by the bumper, hood and engine, and it takes almost 30 to 40 milliseconds before it reaches the car's occupant. In a side The importance of interior design to the potential sales impact, only a relatively thin door and a few inches separate volume of passenger car has always been a major consid- the occupant from another vehicle. This means that door- eration to the automobile stylist. However, despite the fact mounted side airbags must begin deploying in a mere five or that textiles had for a long time played a part in automobile six milliseconds! The head airbag, or Inflatable Tubular manufacture it was not until the early to mid- 1970s that Structure (ITS), looks a little like a big sausage and, unlike these same companies began to realize the role that other airbags, is designed to stay inflated for about five well-designed textile fabrics could play in the design of seconds to offer protection against second or third impacts. attractive interiors (Figure 6). Working with the side airbag, the IT’S is supposed to offer Table 4. Raw Materials used in filter preparation[12] Application Type of filter media Carburetor air filters Mainly nonwoven (wet, dry, needled or spun bonded) Engine oil filters Resin impregnated wet laid nonwoven (paper) Fuel tank filters Activated carbon Cabin interior filters Electro statically charged fiber media, nonwovens, activated carbon, specialty paper Diesel/soot filters Ceramic materials ABS wheel/ brake filters Metal or fiber woven screens Power steering filters Mainly screen fabrics Transmission filters Woven fabrics or needle felts Wiper washer screen filters Woven fabrics Airconditioning recirculation filters Nonwoven / activated carbon Crank case breathe filters Nonwovens Table 5. Various fibers used in automotive interiors and their properties[1, 9, 17, 20] Application Fibre used Properties Seat covers Nylon, polyester, polypropylene, wool Abrasion and UV resistance, attractive design and texture Seat belts Polyester Tensile strength, extension(up to 25-30%), abrasion and UV resistance Carpets Nylon, polyester, polypropylene Light fastness, mouldability Resistance to high temperature inflation gases, durability to storage over Airbags Nylon 6,6 and nylon 4,6 many years, tear strength Seat fire barriers Panox (UCF), Aramid (Nomex,Kevlar-DuPont), Very high FR including restrictions of heat release, toxicity and opacity Inidex (Courtaulds), PBI (Hoechst) of fumes Door trim Polypropylene, nylon polyester

Trunk liners Polyester blends

Journal of Safety Engineering 2012, 1(1): 7-16 13

Figure 6. Textile uses in Car[4]

The reasons for this are: weldability, adhesive properties, vulcanizing properties • Cars were largely designed by engineers, who although (Table 5). talented were not usually textile technologists and so they relied upon their suppliers to alert them to developments. 5.2. Flock and Flock Yarns They tended to develop tried and trusted products due Flock in the car has several positive advantages like: probably then as now, to the huge ‘probability of getting it sorption of moisture, A feeling of comfort, Serviceability, wrong’ Smoothness, Acoustic insulation, Easy-care properties. In • The second reason was that up until this time the textile flock production additives are added to a special polymer industry had not come to regard the automobile industry as a during spinning to improve various properties, the filaments major market for aesthetically designed fabrics. This was then drawn to form a tow. This tow must be cut precisely for due to problems with performance that the existing tech- flock used in the car industry the staple length is 1mm and nologies struggled to produce products, which could with- the linear density is 3.3dtex. stand the critical requirements to abrasive wear and high light fastness. The products that could meet the criteria were 5.3. Synthetic Wood Pulp (SWP) usually unexciting fabrics, probably piece dyed, which of- • This material is produced by Mitsui Chemicals, Tokyo, fered little design potential. Japan. It is estimated that approximately 45 sq meter of textile • These are polyethylene and polypropylene fibrides, material is used in the average car for interior trim, which which are gained directly after polymerization. includes: Seating area , Headliners, Side panels, Carpets, SWP has morphologic characterstics similar to natural Trunks, Door trim, Dash mat[19, 20]. cellulose, synthetic staple fibres and asbestos fibres. In the automotive sector, SWP as binding fibre is more suitable 5.1. Special Requirements for Auto-interior than phenolic resins and PP fine fibres as regards the dis- The common expectancy of the car user is that the tribution properties and minor separation tendencies com- auto-interior should have: Good appearance and aesthetics, pared with phenolic resins SWP creates less odorous an- Good comfort, Easy to maintain, Retention of good proper- noyance. The recycling conditions have been improved, ties even after prolonged usage, Good durability, Wrinkle which is becoming more and more imperative in the auto- resistance, Water and stain proof, Having antistatic and oil motive industry[17]. release property, No or minimum emission, which may hinder driving by fogging or contamination of inside at- 5.4. Fabric Used for Production of Auto-Interior mosphere, Flame resistant for safety, Low costs. The main Nonwovens have better adhesion property than woven and criteria involved in the development of textiles and compo- so binder application is more uniform. They also possess nents in automotive are: Tensile strength, Abrasion resis- higher thickness for a given weight per unit length and so are tance, Pill resistance, Air permeability, compression resis- more voluminous and comfortable. In addition they have a tance, elasticity, light fastness at high temperatures, stiffness, more uniform, smooth and random surface. As a result ease of cleaning, separation force, dimensional stability, nonwovens are preferred for moulded carpets used in mod- flame resistance, anti-fogging resistant, resistance to adverse ern cars. Nonwovens are used globally for the various ap- climatic conditions. The others processing requirements are plications likes floor panels, carpets, boot linings, wheel mouldability, susceptibility to compression, sewability, compartments, parcel shelves, linings for the side panels,

14 Kunal Singha: Strategies for in Automobile: Strategies for Using Automotive Textiles-Manufacturing Techniques and Applications roof linings, car seats, filters, acoustic insulation and the from ethical and sensual comfort, carpets also play signifi- emergence of nonwovens in auto-interiors is helpful in im- cant role in acoustic and vibration control. Road noise is proving cost-effectiveness, redefining carpet value, finding considered as an environmental pollution in few countries. new filters, preventing fogging, working with contours, There are pressures on automobiles to reduce external noise easily customized, attractive, durable, strength and weight, by about 50% (up to 3dB). Carpets are contributing to solve abrasion resistance, thermal protection, flame resistance, this problem. Carpets by providing thermal and acoustic acoustic insulation, air filtration[1]. protection thus directly contribute to safety[9].

5.5. Warp Knitted Spacer Fabrics: Properties 6.1. Types of Carpets Soft handle, Spring comfort(determined by yarn count, The carpets used in cars are mainly of three types: (a) number of stitches, construction and threading-up arrange- Tufted cut-pile (b) Tufted loop-pile (c) Needle-felt ment, Air permeability, Task-oriented comfort behavior, transport of moisture, thermal insulation, refraction of light, 6.2. Noise Control sorption of noise, filtration, requisite dimensional stability, Sound is propagated through the air and by vibration of the longitudinal and/or transverse elasticity on one or both sides, car body and there are three basic methods of reducing it: (a) plastic deformation, fabric can be folded easily, recycla- By absorption (b) By damping (c) By isolation or insulation. ble[15]. In general a thick piece of material will absorb more sound than a thinner piece of the same material (Table 7). Sound 5.6. Evaluation Points for Auto-Seat Covers absorbency is influenced by: density of the material, air • Physical properties like Extensibility, tear, adhesion to porosity of the material, thickness of the material[10, 13]. backing (foam or nonwoven) • Effect of heat, light, moisture and chemicals on physical Table 7. Material used for carpet structure for noise control[13] properties, fastness properties of dyes used Layer Materials used Tufted BCF nylon or needle-punched polyester • Performance criteria (abrasion, pilling, flex), propensity Top decorative or polypropylene-back, latex coated with SBR or layer to fog, odour, soil, static[3-4]. acrylic latex. • Fibre or colour migration to other textiles, which come Thermoforming Polyethylene powder, meldable fibres, EVA or a in contact with it and special demands like flame proofness, layer further thick layer of compounded SBR latex. ‘heavy layer’ of EPDM, shoddy fibres or poly- thermal insulation, water proofness[7], sound dampening. Acoustic layers The type of fabric used for seating varies from location to urethane foam location: • Both woven and knitted fabrics are used in Europe and USA. In USA, woven velour is preferred whereas in Western 7. Door and Side Panels Europe, the car builders are favouring Knitted fabrics. As in the other areas of the cars, the vehicle models very • In Asia, however the majority of the car seating fabrics much dictates the fabric type used on door and side panels. is knitted. In Japanese market, the car builders have always The choice is dictated by cost considerations consistent with been favouring woven velour fabric and this trend looks desired appearance and aesthetics. The fabrics used for doors unlikely to change[14, 17]. etc should have high degree of stretchness. This can be obtained by incorporating elastomeric yarns into structure of 5.7. Seat Comfort fabrics. Now a layer of foam is added to the door panel fab- There are some standard guidelines for the comfortness in rics to get a more luxurious touch. Still development includes a car seat considering different parameters (Table 6). the utilization of high pile polyester fabric without distortion and to eliminate Vinyl backing[17]. Table 6. Constructional guidelines for car seats with optimized comfort[14] 7.1. Headliners Textile fabric better than leather(natural or synthetic). Velours At one time the headliner was simply a covering for the Covering better than flat woven better than flock Part hygroscopic fibres better than 100% synthetics metal roof inside the car and consisted of a piece of fabric, Lining Hygroscopic wadding (e.g.WO) better than foam pad PVC or some other material simply ‘slung’ i.e. held in place Spring core/rubberized hair pad better than foam pad, Cut Cushion only at a few points. Some important requirements of head- foam better than molded foam pad Perforation of foam pad components liners are the lightweight, thin profile but rigid without any Seat cushion and back as thin as possible, Open frame tendency to buckle, flex or vibrates directional stability, Ventilation layer (spacer fabric) with/without forced air stream Design If large side supports, grooves in seat cushion and back rest aesthetically pleasing, soft in touch[14]. 7.2. Trunk Liners 6. Carpets Cars with trunk liners are making rapid gain in the headliner market. Now a days, the automobile manufacturers are There are about 3.5 to 4.5 sq. mt carpet in each car. Apart making lining attached to the front and rear walls, in many

Journal of Safety Engineering 2012, 1(1): 7-16 15

cases attached to sidewalls also. This gives a most luxurious 8. Future Application of Automotive appearance and also serves as protection to both exterior walls and to trunk content such as luggages perfect to date. Fabrics The liners must be decorative and functional, yet have rela- • Listings: Listings are strips of fabrics used to attach tive cost. These are usually made from waste fibre that are upholstery to the frame or moulded seat composite. These needled and then naturated with elastomerics materials. are interfaces that must be strong, have ample seam strength However, even spun bonded polypropylene is also used as a and low seam slippage, and must be able to hold a metal substrate for a foamed rubber material that is used as trunk fastener or staple[18]. liner[14, 18]. • Insulator pads: Insulator pads are composites that act as 7.3. Landau Tops a buffer between the foundation and upholstery. • Map pocket liner: Map pocket liner is a backing that Landau tops give the car an extra leathery look. The top of supports the trim fabric.Tie downs: Tie downs are fabrics the car interior is generally covered with a nonwoven fab- attached to an extended olefin polymer bead. These are ric[4]. Now a days needle nonwoven is generally used. The similar to listings in that they are used to attach upholstery to process treats the needled polyester nonwoven with finishing the frame assembly[19-20]. materials to prevent wicking and rusting of the metal roof under the top. The extreme care is taken in handling the Landau top material to protect matter that would interfere 9. Conclusions with the subsequent dielectric sealing process used in assembly plants[9]. Manufacturers are trying their best to make In today’s agile world, many service providers are mar- a fabric for top assembly having lightweight, good fastness keting their products under slogans likes instant connectivity, or rubbing and also good-looking appearances. quick service. Everyone wants quicker services, faster car. As per world health organization, Road accidents are a 7.4. Parcel Shelves worldwide problem and now result in over, 1.2 million peo- Parcel shelves, also referred to as package trays or the ‘hat ple die every year from road crashes all around the globe. rack’ are now almost invariably covered with needle- Occupant restraints, is the best solution such as seat belts and punched nonwoven mainly in polypropylene or polyes- air bags, are highly effective in preventing death and injury ter[10]. Parcel shelves range in size from relatively narrow from traffic collisions. Seat belts are easy to use, effective components in saloon cars, to a much larger and wider article and inexpensive means of protection in an accident. Use of in hatchbacks[17]. airbags in a vehicle provides additional safety but it is not an alternative to seat belts. They co-exist to provide absolute 7.5. Dashbroad safety to the passenger. This is so because the airbags provide protection against head-on collision while the seat belts The dashboard, probably the hottest area in the car interior, provide protection irrespective of the direction of crash. Air offers some opportunity for textiles, although a very limited bags would reduce motor crash fatalities by an estimated number of car models use fabric at present in this very de- 10-15 per cent over and above the 40 per cent injury- reduc- manding application[9]. The dashboard shape being highly tion provided by seat belts alone (if worn). Autoliv estimated, curved and also complex, to accommodate controls and seatbelts are expected to reduce the overall risk for serious instruments, presents many problems to the textile tech- injuries in crashes by 60-70% and the risk for fatalities by nologist. It could probably only be obtained by knitting, and about 45 percent. Automotive filters can serve to the better 3D knitting would be eminently suitable. Performance cri- condition of the vehicles as well as reduce the environment teria fulfilled by textiles are: low gloss (no glare or reflec- pollution. The noise absorbent automotives helps to reduce tions on the windscreen), soft touch, pleasant aesthetics, in noise pollution. non-fogging, non-odorous, UV stability, resistance to heat ageing, resistance to low temperature, high abrasion resistance[12]. 7.6. 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